1. Department of Physical Chemistry II, University of Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany
2. Department of Inorganic, Analytical, and Applied Chemistry, University of Geneva, Sciences II, 30, Quai Ernest-Ansermet 1211 Geneva 4, Switzerland
3. Centre de Recherches sur les Macromolécules Végétales, CNRS, affiliated with Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France